1. Field of the Invention
The present invention relates to a bone jointer in order to carry out junction, for example, of a fractured part at a neck of femur. More particularly, the present invention relates to that in which junction of the bone may be carried out corresponding to various types of fracture by easily obtaining the strong fixed state.
The present invention also relates to a bone jointer fixing tool used when the bone jointer is used in order to carry out junction, for example, of a fractured part of the neck of femur. More particularly, the present invention also relates to that in which the bone jointer may easily and accurately be fixed corresponding to various types of fracture.
2. Description of the Related Art
There is an example of bone jointer disclosed in the prior art, such as the Japanese utility model registration No. 3044923, which is owned by the applicant of the present invention, as illustrated in FIG. 20.
FIG. 20 illustrates the state of fracture at a neck 300a of a femur 300, as well as the structure of a bone jointer in order to carry out junction of such a fracture part, which is shown by letter A.
There is a tube plate 301 placed along the side of the femur 300. A hemispherical shape of receiver 303 is formed at the top of the tube plate 301 as shown in FIG. 20. The receiver 303 has a penetration hole 305.
A hole is formed in the femur 300, through which a tube 307 is placed, thus the tube 307 is positioned inside the receiver 303. The tube 307 has a hemispherical shape of head 309 and is movably engaged with the receiver 303 via the head 309. The tube 307 has a hollow part 311, and an internal thread 313 is formed on the inner periphery of the head 309. The receiver 303 has a matt (i.e. slightly rough or sandy) surface, and the same is true to the surface of the head 309. Accordingly, when the head 309 is received by the receiver 303, a large frictional force as well as a large fixing force may be obtained.
There is a lag screw 315 provided with a shaft 317 of which cross sectional shape is hexagon. The shaft 317 has an external thread 319 formed at the top thereof, and also has an internal thread 320 formed on the inner periphery of the basement (that is, the lower side of FIG. 20) thereof. With this structure, a hole has been formed in advance from the femur 300 toward a bone head 300b, and the lag screw 315 is inserted in this hole. Then the lag screw 315 becomes engaged with an internal thread provided on the hole of the bone head 300b.
There is also a set screw 321 provided on the outer periphery of the receiver 303 of the tube plate 301. The set screw 321 has an external thread 323 which is to be engaged with the internal thread 313 of the tube 307. The compression screw 325 has an external thread 327 to be engaged with the internal thread 320 of the lag screw 315.
Further, the tube plate 301 has a plurality of penetration holes 331 through which the cortical bone screws 329 each serving as the fixing screw may respectively be penetrated. The tube plate 301 also has another penetration hole 335 into which a canulated screw 333 may be penetrated.
According to this structure, when there is a fracture at the neck 300a of the femur 300, for example, a predetermined depth of hole is first drilled from the femur 300 toward the bone head 300b, then the internal thread is cut in the bone head 300b. After that, the lag screw 315 is inserted to be engaged with the cut internal thread of the bone head 300b, and the tube 307 is also inserted therein. In such a state, the basement of the lag screw 315 is inserted in the hollow part 311 inside the tube 307.
The tube plate 301 has been placed along the side of the femur 300, and the set screw 321 is inserted in the penetration hole 305 of the receiver 303 of the tube plate 301. Thus the set screw 321 is engaged with the internal thread 313 of the head 309 of the tube 307 in order to fix the tube 307 on the tube plate 301. Then the compression screw 325 is inserted in the set screw 321, so that the compression screw 325 may be engaged with the internal thread 320 provided inside the basement of the lag screw 315. Accordingly, the lag screw 315, as well as the bone head 300b, will be drew toward the femur 300 in order to apply the pressure to the fracture part A. Then the plurality of the cortical bone screws 329 and the canulated screw 333 are screwed into the femur 300 from the outside of the tube plate 301 in order to fix the fracture part.
However, the prior art has the following disadvantageous point.
According to the prior art as above discussed, both the head 309 of the tube 307 and the receiver 303 of the tube plate 301 are hemispherical shapes, so that the tube 307 may move in all directions relative to the tube plate 301, in order to cope with any directional force of the tube 307 as well as the lag screw 315 applied to the tube plate 301.
However, the connection of the set screw 321 to the tube 307 is difficult, and even after the set screw 321 has been connected to the tube 307, there may occur another problem of the improper positioning due to a clearance between the set screw 321 and the penetration hole 305 of the tube plate 301. This will cause the inaccurate positioning as well as the weakened fixing force.
Further, when this type of bone jointer is fixed, there has been a demand that the fixing of the jointer should be carried out easily and more accurately.